Has anybody made a proximity sensor using simple IR transmitter and receiver pair? How is the performance? I want to determine distances upto 50 cm (moderate accuracy will do). I will be testing this out in a couple of days' time. I want advice on how to make it as accurate as possible.
Your subject text and message text don't quite agree here. Are you wanting a proximity sensor, or a distance sensor?
This type of sensor is not capable of measuring distance. It is only for proximity: if the object is within a distance that reflects back enough light to be registered. As different types of materials reflect different amounts of infrared light, it is not possible to simply gauge distance by the strength of the reflected light.
You need an IR sensor that works using light parallax or some other technique. The most common parallax distance sensors are those made by Sharp. They're available from a number of robotics specialty outlets.
I would avoid a basic sensor using unmodulated light. They're okay for playing around, but for anything consistent you'll want modulated light, using an IR receiver tuned to that modulation. Kits and circuit examples abound on the Internet for these. Check out Google for the phrase "IRPD."
-- Gordon
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